Grinding device



July 21, 1942. J. Y. BLAZEK GRINDING DEVICE 2 Sheets-Sheet 1 Filed Oct. 27, 1959 INVENTOR. Jo HN Y BLAZEK AT'T-omsaiy y 1942- J. Y. BLAZEK 2,290,730

GRINDING DEVICE Filed on. 27, 1939 2 Sheets-Sheet 2 INVENTOR. JOHN 7. B1. AZEK ATTORNEYS.

Patented July 21, 1942 UNETED STATES PATENT OFFICE GRINDING DEVICE Application October 27, 1939, Serial No. 301,649

8 Claims.

This invention relates generally to a grinding tool, but has reference more particularly to a grinding tool for grinding objects to make them truly cylindrical. A grinding tool embodying this invention is particularly well adapted for grinding the bearing surfaces of crankshafts and the like, especially those of vehicular power units.

My grinding tool is of the separable ring-like frame type, which may be separated to allow it to be brought into working engagement with the bearing portions of objects having projections on each side thereof which interfere with sliding the tool on. I contemplate the use of arcuate shoes which, by means of the ring-like member, are maintained in working relation with the object to be ground.

The gist and primary object of this invention is the provision of an abrading element which is supported by said shoe.

Another object of this invention is to provide an improved manner of supporting, driving and retaining the abrading element in such a way that it will be less apt to be injured by the stresses and strains to which it is subjected.

Another object of this invention is to provide means for resiliently urging said shoes inwardly, means for preventing said shoes from falling out of said ring-like frame, and means for tilting or tipping said shoes with respect to said frame.

A further object is to provide an improved clamping means for readily clamping or unclamping the members of the separable ring-like frame.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description set forth in detail certain structures embodying the invention, such disclosed means constituting, however, but one of various structural forms in which the principle of the invention may be used.

In said annexed drawings:

Fig. 1 is a cross-sectional view of a device embodying this invention taken on a plane perpendicular to the axis thereof;

Fig. 2 is a view taken on the plane 2-2 of Fig. 1;

Fig. 3 is a fragmentary view showing a device embodying this invention disposed in working relation to a cylindrical object to be ground;

. Fig. 4 is a view taken on the plane 4-4 of Fig. 3; a

Fig. 5 is a perspective view of an abrading element which is part of this invention;

Figs. 6 and 7 are views similar to Fig. 5 and each show a modification thereof.

Referring now to the drawings and more particularly to Figs. 1 to 4, the device illustrated is seen to comprise a pulley made upof two substantially half-ring members It and H, each having a peripheral groove I2 adapted to receive a driving belt. Positioned within recesses H2 is a link I5, which, by means of pins ll, pivotally connects the two members so that they can be swung until the beveled ends I8 thereof meet, at which time the pulley can be placed about a shaft to be ground.

In order to lock the pulley about the shaft, a latch bar 20 is disposed within a recess 2| and is pivotally pinned at 22 to one member It or II and has an outwardly extending notch 23 adapted to engage a pin 24 carried by the other member I0 or II. A spring 25 urges the latch bar 20 upwardly and into engagement with pin 24, and a pin 26 limits this upward urging effect so that the cam surface 21 of the latch bar 20 engages the pin 24.

When the pulley rotates centrifugal force prevents disengagement of the pin 24 from the notch 23.

Along the inner periphery of each of the ring members It and II is an arcuate shoe 3% which is freely held in place by engagement with a bolt 3| which projects loosely through a radial opening 32 of a ring member In or I I, so that the shoes may be shifted radially or axially with respect to the members It] and H.

To urge the shoes radially inwardly spaced plungers 33, pressed inwardly by spring 34, which is backed by screw plug 35, occupy a recess 38 on the outer periphery of the shoes 35. The plungers 33, spring 34 and plug screw 35 are disposed within a cavity 31 in the members it and II.

Flanges 40 extending axially from members H1 and II are provided with threaded holes in alignment with openings 32, for reception of screws 4| which bear against the ends of the shoes 30, so that by adjusting screws 4 I, the shoes can be tilted or caused to lie in conical relation.

One abrading element shown in Fig. 5 lies against the inner periphery of each shoe 3;} and is seen to comprise an arcuate metallic backing 56, which has a flange 5| extending outwardly, preferably radially, to provide a shoulder slotted as at 52 which, by means of screws 53 and lock bar 54 are anchored to an outward face of and driven by the shoes 30. The junction of this outward face and inner periphery of shoe 30 is rounded, as at 55, the purpose of which will be hereinafter described.

Secured to the inner face of metallic backing 50 is a layer of granular abrasive material which may be either directly bonded thereto, or which may be bonded to a fibrous sheet, such as cloth or paper which in turn is bonded to the metallic backing 50.

The metallic backing 50 is thin and may be resilient, so that it separates itself from the shoes 30, as shown in Fig. 1, or it may be less resilient or stiff, so that it will maintain the shape it has in Fig. 3 when the crankshaft 51 is removed. When the backing 50 is very stiff and normally maintains the shape shown in Fig. 3, the net effect thereof is negligible and the abrasive could be secured directly to the shoes 30 with equal expediency.

Instead of making the backing so that its uniiexed cross-section is larger in radius than is the radius of the inner periphery of the shoes 30 as in Fig. 1, it may be made smaller in radius than is the said radius of the shoes 30. The difference is that in the former case the insertion of the crankshaft will decrease, while in the latter case it will increase the radius of curvature of the backing 50.

The advantage of securing onto the backing 55 a fibrous sheet which has secured to it an abrasive layer is that the granular abrasive may be better secured to the fibrous sheet than it can be secured directly to the metallic backing 50. Also,-

a better bond can be had between the backing 50 and the fibrous sheet than between the backing 55 and a layer of granular abrasive, The layer of abrasive can be made more uniform on a long fibrous sheet or strip which is then cut to suitable size. If a zone of the abrasive loses its bond with the metallic backing 50, the abrasive comprising such zone is completely lost, but if a zone of the bond between the fibrous sheet and the abrasive breaks down, the sheet will retain its bond with the backing 50 in the area of the same zone and the abrasive of such zone is not lost. Moreover, if the abrasive wears down, the fibrous backing still remains and prevents exposure of the metallic backing which would scratch the surface of bearing being ground.

In Fig. 5 the abrasive layer 56 is continuous over one entire surface of the metallic backing 50. Alternative constructions of the abrading element are shown in Figs. 6 and 7'. In Fig. 6 the abrasive layer is not continuous but is broken by staggered zones 65. These zones can be best created by punching holes in emery cloth or emery paper before securing it to the backing 56. These zones function to prevent packing or loading of the abrasive layer and consequently results in a better finish. However, they weaken the abrasive layer.

In Fig. 7 there is shown two spaced strips 65 of abrasive. These strips may be of the same size grain abrasive or each strip may have a different size grain, This latter arrangement is particularly useful when a tapered or conical bearing is encountered because a coarse strip may be used on the larger part while a fine strip may be used on the smaller part of thebearing.

It is to be understood that the only difference between Fig. 5 and Figs. 6 and 7 are the zones and strips,. respectively.

Operation Let us assume that a tapered out-of-round bearing is to be trued. When the pulley members [0 and II are swung open and placed about a crankpin to be trued, they are manually brought together, causing the cam surface 21 of the latch bar 2|] to cam the notch 23 into engagement with the pin 24 causing the abrasive element to substantially conform to the out-of-round configura tion of the bearing, but having the maximum pressure exerted against the bearing at the points where its out-of-round is at a maximum. The screws 4| are adjusted to counteract the taper and as the grinding progresses and the taper vanishes, the plungers 36 move the shoes inwardly towards the bearing and away from the screws 4|, so that they become inactive and the shoes 30 assume truly cylindrical relation. The pressure exerted by springs 31 may be adjusted by manipulation of screw plug 35.

The shoes 30 preferably are not as wide as the bearing and as the pulley rotates it should be manually moved back and forth between the crank arms.

To grind bearings of different size diameters, shoes 35 and complementary abrasive elements are employed whose inner radius of curvature conforms to that of the bearing. For slight variations in bearing diameters, shims may be employed between shoes 30 and the abrasive elements.

This tool is particularly well adapted for grinding crankshafts while its main bearings are journalled to the motor block. All that is necessary is to remove the oil pan and disconnect the connecting rods from the crankshaft.

Since the abrasive elements are free at one end, the pulley should be rotated clockwise, as is illustrated by the arrow of Fig. 1.

To remove the pulley from the crankshaft, a small lever is inserted in the recess 2| with one of its ends resting on the step 10 of the latch bar 25 and its mid-portion pivoting about the edge H of recess 2| as a fulcrum. Then, by raising the step 10, the notch 23- disengages the pin 24, whereupon the resiliency of the backing 5E! and the plungers 36- cause the members l0 and H to swing open, permitting the pulley to be manually removed.

It is thus seen that a device embodying this invention can be easily locked about and removed from the crankshaft.

It is also seen that since the abrasive layer is secured to a metallic backing, that it is less apt to be injured by the stresses and strains to which it is subjected. The rounded junction 55 prevents bending stresses in the fabric from fracturing or weakening the same.

It is further seen that the shoes to a limited extent freely float, cannot fall out, are resiliently urged inwardly and can be tilted.

This application is in part a division and in part a continuation of copending application Serial No. 244,791.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the form or construction herein disclosed, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed.

I therefore particularly point out and distinctly claim as my invention:'

1. In a device of the character described, a

split ring-like frame comprising two members adapted to lie around a shaft, a pin carried by one of said members and an element having a notch pivotally carried by the other of said members, said notch being adapted to engage said pin and a spring urging said notch into engagement with said pin.

2 In a shaft grinding tool, a split ring-like frame comprising two members adapted to rotatably lie around a shaft, a pin carried by one of said members, an element having an outwardly extending notch adapted to pivot about the other of said members for engaging said pin, said element having a greater mass on one side of its pivoting point than on the other side thereof whereby centrifugal force set up by said mass urges said notch into engagement with said pin.

3. In a shaft grinding tool, the combination of a split ring-like frame comprising two members adapted to lie around a shaft, a pin carried by one of said members, an element having an outwardly extending notch pivot'ally carried by the other of said members, said notch being adapted to engage said pin, and a spring interposed between said notch and the pivoting point of said element urging said notch into engagement with said pin.

4. In a tool adapted for grinding a crankpin of a, crankshaft and the like, the combination of a ring-like frame adapted to lie around said crankpin, and an arcuate abrasive strip-like element extending along the inner surface thereof, said element comprising a backing having two circumferentially extending strips of abrasive thereon, one of said strips having abrasive grains of one size and the other of said strips having abrasive grains of another size whereby rotation of said frame relatively to said crankpin results in abrading one circumferential portion of said crankpin more than another circumferential portion thereof.

5. In a method of producing a substantially cylindrical surface from a conical surface, the

step of simultaneously abrading the high and the low portion of the conical surface with a coarse abradant at the high portion and a fine 'abradant at the low portion until the conical surface is substantially cylindrical and then simultaneously abrading both portions with the same grade abradant.

6. In a method of producing a substantially cylindrical surface from 'a conical surface, the step of simultaneously abrading the high and the low portion of the conical surface with a coarse abrasive at the high portion and a fine abrasive at the low portion until the conical surface is substantially cylindrical.

7, In a shaft grinding tool, the combination of a ring-like frame having a substantially cylindrical inner surface adapted to lie around a shaft, and an abrading element extending along said inner surface, said element comprising a substantially cylindrical metallic backing having adhesively secured thereto abrasive segregated into two axially spaced circumferentially extending zones, the size of abrasive of one zone being different from the size of abrasive of the other zone.

8. In a tool adapted for grinding a crank pin of a crankshaft and the like, the combination of a ring-like frame having a substantially cylindrical inner surface adapted to lie around a crank pin, and an arcuate abrasive strip like element extending along the inner surface thereof, said element comprising a substantially cylindrical backing having two circumferentially extending axially spaced strips of abrasive thereon, one of said strips having abrasive grains of one size and the other of said strips having abrasive grains of another size whereby rotation of said frame relatively to said crank pin results in abrading one circumferential portion of said crank pin more than another circumferential portion thereof.

JOHN Y. BLAZEK. 

